Comment

Do you have some setups like precomputed visibility which can only be done on CPU currently?

Also I remember that currently the calculation of volumetric lightmaps doesn't have a proper progression display, so if you see the GPU is not idle it may be working on that.

I think I'm getting closer to the problem. The GPU calculation gets stuck, the GPU stops working, but Lightmass.exe sits at 62% CPU usage. This only happens when I'm using "Sparse Volume Lighting Samples". Are these supported?

Comment

I think I'm getting closer to the problem. The GPU calculation gets stuck, the GPU stops working, but Lightmass.exe sits at 62% CPU usage. This only happens when I'm using "Sparse Volume Lighting Samples". Are these supported?

Sparse Volume Lighting Samples are computed entirely on CPU now. I believe it should be the problem.

Comment

Sparse Volume Lighting Samples are computed entirely on CPU now. I believe it should be the problem.

I see! Does that mean the lighting needs to be recalculated entirely on CPU for the Sparse Volume Lighting Samples to work? I'm just trying to get an idea of how long it should take, as it seems to take forever and there is no output on the log giving me an idea that progress is indeed happening.

By the way, the results are amazing!!!!

Comment

I see! Does that mean the lighting needs to be recalculated entirely on CPU for the Sparse Volume Lighting Samples to work? I'm just trying to get an idea of how long it should take, as it seems to take forever and there is no output on the log giving me an idea that progress is indeed happening.

By the way, the results are amazing!!!!

Unfortunately, yes. In fact the recalculation is not implemented so currently Sparse Volume Lighting Samples won't compute properly (they'll simply turn black, or have only direct lighting).

Edit: maybe I can come up with a quick fix to move their caluclation onto GPU

Comment

I've updated GPULightmass to support sparse volume lighting samples. Please redownload to get the newer version. Note that the samples don't get proper progress display so you can only tell by looking at GPU load.

Comment

Also there are some screenshots of Brute Force (GPULightmass) vs Irradiance Caching (Lightmass, default production quality):
2min50s (GTX1080) vs 8min10s (i7-6700k), Simplified SunTemple
If you look at the timings only then it is not very impressive. However the quality has a big difference. If you want to tweak Lightmass parameters so that it prduces same quality images as GPULightmass then I believe it'll be at least 10x slower:

The downside is GPULightmass has noise while Irradiance Caching has 'built-in' smoothing. While a denoiser is definitely on the plan, I'm still working on the sampling algorithm to get better quality samples.

Edit 04/14/2018: I made some changes to the sampler to suppress the artifacts on the wall:

Comment

Comment

Looks amazing! The quality of the shadows is much higher and I notice that you don't seem to get the variations induced by multi-threading. Look forward to trying it out and hope Epic adopts this method officially.